During the initial design stages of the guest bathrooms, we decided to use our master bathroom as an inspiration. We continue to be pleased with the master bathroom renovation, and knew that repeating the vanity and countertop design would bring continuity throughout the house.

However, we were looking to scale the cost of the vanity down a bit, and instead of using bluestone as the vanity top again, decided to use poured concrete.

Bluestone vanity top inspiration

John did the technical research of pouring concrete into molds, and I helped determine the color and texture we wanted to achieve.

The internet is booming with concrete these days, so our inspirations were boundless! There were almost too many opinions...

We focused on a simple design, that would easy display a self-rimming drop in sink. For this first concrete pouring attempt, we opted not to add color.

Here's the play-by-play of the sink and shower curb fabrication.

Create a Mold:

Using melamine, we created a mold for the curb and counter top. The dimensions are completely up to your needs, sink requirements and space.

Melamine is a great material because the surface is smooth and concrete doesn't adhere to it. We screwed the sides together with dry wall screws (that would be easy to unscrew later in the process).

We then placed the molds on sawhorses, and checked to ensure the whole setup was level. THIS IS SO IMPORTANT. We used scraps of wood/shims to make everything square. Remember, however the concrete is poured and settles is how it will harden.

Use a level and shims to ensure the mold is straight before pouring.

This mold was actually constructed with a movable center “stop” so we could use the same mold to achieve shower curbs of the same width, but different lengths.

Lubricate Mold:

With a rag, use a lubricant (we used motor oil) to generously coat the inside of the mold. This will ensure that the concrete does not set too hard on the surface of the mold and will aid in the mold removal once it’s set.

As an alternative, we think cooking spray might be even easier to apply and get in the corners of the mold.

Mix Concrete:

In a large masonry pan, mix concrete with water until a “chunky oatmeal” consistency is achieved. We do not recommend a bucket, a larger mixing surface makes for easier mixing with a shovel.

We then added the Flow Control, which chemically provided move fluidity to the concrete mixture. Magically, the concrete will have the consistency of liquid without compromising the strength of the mixture.

Flow Control chemically provided move fluidity to the concrete mixture

Fill Mold with Concrete Mixture:

About half way through the mold filling step, stop and add in pieces of rebar to reinforce the concrete structure and add rigidity.

Then, fill the remainder of the mold, fully covering the rebar.

Vibrate Mold Vigorously:

This step helps to bring air bubbles within the concrete mix to the surface. The more time (minimum 10 minutes) and energy you spend on this step, the less holes you should have on the surface of the finished product.

We used a palm sander (sans sanding pad) to create the vibration on the underside of the mold.

Let Concrete Set:

We let our molds set for at least 24 hours, but we experienced some cracking initially. We would recommend letting your molds set for a minimum of 24 to 48 hours. Keep your location in mind, and the weather forecast, so your molds are not in direct rain, sun or snow and can dry as evenly as possible.

Remove molding:

After an adequate drying time, remove the mold screws entirely.

Flip the Concrete:

Once the mold is removed, you will need to flip the entire concrete structure, so the inner side is exposed.

Seal Concrete:

We opted to use a Low Lustre Concrete Sealer. At this point, if you would like to color or stain the concrete, there are a ton of paint options available. We did look into this, but in the end, opted for the natural grey concrete color achieved from natural drying.

We put the concrete sealer in a spray bottle, distributed it evenly across the whole surface, and used a foam roller to spread it out. We applied three coats, with 1-hour of drying time between coats.

Finished Results:

Is this a project you think you could tackle on your own? Tell us what you think below!

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